Feng Zekun

Effects of Fe2+ content in raw materials on Mn-Zn ferrite magnetic properties

Abstract The magnetic properties of Mn–Zn ferrite such as initial permeability, saturation magnetization, Curie temperature, resistivity and power loss are affected greatly by the Fe 2+ content in the raw materials. The experimental results show that low resistivity ( ρ ) and high eddy current loss ( P e ) are induced by the superfluous Fe 2+ content in the raw materials; the scant Fe 2+ content in the raw materials will increase hysteresis loss ( P h ) and decrease Curie temperature ( T c ), saturation magnetization ( M s ) and initial permeability ( μ i ).

Wide-band electromagnetic wave absorber of rubber-ferrite

Two different compositions with Ba(Ti/sub 0.5/Co/sub 0.5/)/sub 2.1/Fe/sub 9.9/ O/sub 19/ and Ba(Ti/sub 0.5/Co/sub 0.5/)/sub 3.2/Fe/sub 8.8/O/sub 19/ of barium ferrite with a magnetoplumbite structure (M-type) had been obtained by conventional ceramic technology. The complex permeability and permittivity of the materials were measured in the 2-18 GHz band. Ba M-type ferrite materials mixed with polyvinyl chloride, plasticizer and frit are pressed to form flakes (180 mm/spl times/180 mm/spl times/2 mm) of rubber-ferrite. The absorption properties of the single layer rubber-ferrite absorber are measured by an Agilent 8722ES network analyzer (2-18 GHz). Compared with the theoretical calculation, it was found that preferable properties of microwave absorption were obtained by using a bank of two ferrite materials singly over a narrow frequency region. Almost all of the samples in the multi-layer rubber-ferrite absorber exhibited a minimum reflection loss less than -10 dB with a thickness (d/sub m/) 22 mm.

A study of dispersion characteristics of magnetostatic surface wave (MSSW) delay lines in the multiple layer films

Abstract A correct dispersion equation for MSSW propagating in multiple layer films has been derived. The delay-frequency curves with the various parameters of the film and the applied field have been given. This paper first reports some experimental results of the LPE grown multiple layer films (GGG-La; YIG-GGG-La : YIG) and the MSSW delay lines consisting of the multiple LPE films with one side metallized. The device characteristics of a linear delay over 400 MHz bandwidth in the 3.6 to 4.4 GHz frequency range have been exhibited to be in agreement with theory.